Substantially important in view of the operation of the lock is the mainly free mobility of the lock in its longitudinal direction and its rotary motion about its longitudinal axis in the course of the lock's opening and closing motions. If the fit of the lock is too loose, this causes a rough, clanking and binding reciprocating motion of the lock, which gives rise to malfunctions when the lock is operated rapidly. Excessively tight fit prevents or hampers the unrestricted action of the lock. Accurate and exact fitting of the lock in the lock frame constitutes the basis for the fire arm's reliability in service and its accuracy.
The crank locks known in the art are made of steel. The combination of the difficult machinability of a material presenting adequate strength characteristics and of the narrow and exact dimensional tolerances implied by the dimensioning of the lock and by its fitting into the lock frame results in high manufacturing costs of the crank lock. The price of a high-class crank lock accounts for a remarkable share in the total price of the firearm.